Electron beam devices



April 20, 1965 R. ADLER 3,179,838

ELECTRON BEAM DEVICES Filed July 25, 1962 INVENTOR.

Roberzf c/ ldZer Filed .luly 25, 1962, Ser. No. 212,408 3 Claims. (Cl. 3l5--3) The present invention pertains to electron beam devices and more particularly to an improved phase shifter for electron beam Waves.

This application is a continuation-in-part of a copending application of Robert Adler, Serial No. 205,591 for Electron Beam Devices and assigned to the present assignee. That application specifically describes an apparatus which serves as a phase shifter for synchronous waves as well as cyclotron waves of finite phase velocity. As is known in the art, synchronous waves have a phase velocity equal to that of the electron stream on which they are present for all frequencies of signal excitation. However, cyclotron-type waves have phase velocities which may range from a relatively low finite value to an infinite value, depending on the frequency of signal excitation.

It is a major object of the present invention to provide a new and improved phase shifter for electron beam waves.

It is a more specific object of the invention to provide a phase shifter for electron beam Waves of the cyclotron type.

it is a further object of the invention to provide a phase shifter which is linearly adjustable.

In accordance with the above objects a cyclotron wave signal-energy phase shifter comprises means for projecting a stream of electrons along a predetermined axis and means for producing a magnetic field aligned parallel to the axis. An input coupler having signal energy input means produces a cyclotron electron wave on the electron stream at a predetermined signal frequency. An output coupler derives output signal energy from the electron stream at the predetermined signal frequency. Additional means adjustable during operation of the phase shifter is included for selectively changing the strength of the magnetic field in a region intermediate the couplers to shift the phase of the output signal controllably with respect to that of the input signal and in an amount proportional to the magnitude of strength change selected at any given time.

The features of the present invention which are believed to be novel are set forth with particularity in the appended claims. The invention, together with further objects and advantages thereof, may best be understood by reference to the following description taken in connection with the accompanying drawing, in the several figures of which like reference numerals identify like elements, and in which:

FIGURE 1 is a perspective diagrammatic view of a cyclotron wave signal phase shifter constructed in accordance with the invention; and

FIGURE 2 is a sectional view taken along line 22 of FIGURE 1.

Referring to FIGURE 1, the device includes an input coupler it) having two parallel rectangular plates 10:: and 1%, which is otherwise known as a parallel plate Cuccia coupler, and an output coupler 11 identical in construction to the input coupler. The opposing plates of each United States Patent 3,17%,83d Patented Apr. 20, 1965 ice coupler are placed on opposite sides of a Z axi (shown by the dashed line) along which a stream of electrons 12 is projected from a cathode 13 to a collector 14. Input signal energy is applied from a source 16 to coupler ll). Output coupler ll derives output signal energy from electron stream 12 for transmission to a load 17. The couplers and the associated elements are disposed in an evacuated envelope (not illustrated).

Electron stream 12 is subjected to a longitudinal magnetic field indicated by arrow H which is aligned parallel to the Z. axis. it is usually most convenient to develop the magnetic held by means of a solenoid (not shown) within which the tube envelope is contained.

Input and output couplers ll) and ll of the illustrated construction are capable of coupling only to a fast cyclotron wave of substantially infinite phase velocity. Cyclotron waves of finite phase velocity may also be utilized in the present invention by providing couplers suitable for interacting with cyclotron waves of finite phase velocity. A number of such couplers are disclosed and claimed in co-pending application Serial No. 738,546, filed May 28, 1958 by Robert Adler.

To provide a controllable phase shift between the input and output signal, a control solenoid 15 is placed about electron stream 12 intermediate input coupler 19 and output coupler 11. Direct current I is passed through the control solenoid to create a magnetic field which either adds to or subtracts from magnetic field H over he length of the control solenoid, depending on the direction of current I. By varying I, the total magnetic field in the space encompassed by the control solenoid is adjusted.

The phase constant or propagation constant of a cyclo tron wave is given by the expression where t represents the number of waves on the beam in 21 units of length; U0 is the drift velocity of electron stream 12, w the signal frequency and w the cyclotron frequency, both expressed in radians per second. The expression applies directly to fast cyclotron waves; for slow cyclotron waves, a plus sign may be substituted for the minus sign in the numerator.

The total phase shift 5 in radians over a length L is equal to For a coil of fixed length L, phase shift is thus proportional to (3. The first expression indicates that a change of w caused by a change in magnetic field produced in turn by an applied current 1, causes a linearly proportional change in output phase This linearity is a fundamental property of the phase shifter according to the invention. It is of great importance wherever such a linear relationship is required.

From the above expression it is also apparent that a change in n will also affect the phase shift. The above mentioned application, of which this is a continuation-inpart, specifically utilized this method of phase shifting, by varying the drift velocity of the electron stream. However, in the special case Where w=w and a fast cyclotron wave is utilized, the numerator in the first equation above is zero. In that case, variation of M0 is ineffectual to vary enraaae Cuccia couplers and operated under the condition w w Solenoid 15 was designed with the following dimensions:

Inch

Wire diameter d=.020 Coil diameter measured to the inside surface of the coil D=.030

Distance between centers of turns l=.030

Length of coil L=.660

Thedesign of the above coil is not critical and is suitable for a wide frequency range. The two Cuccia couplers 10 and 11 were designed to have an optimum frequency of operation of 1,305 megacycles. The following D.C. potentials were applied to the circuit elements with respect to cathode 13:

Volts Input coupler 1t) l Solenoid 15 7.8 Output coupler 11 10 Collector 14 80 A direct current of one-half ampere in solenoid 15 was suflicient to produce a phase shift of 180 degrees.

Thus, the present invention provides an improved phase shifter which exhibits linear phase shift of signal energy when associated with electron beam Waves of the cyclotron type.

While a particular embodiment of the invention has been shown and described, it will be obvious to those skilled in the art that changes and modifications may be made without departing from the invention in its broader aspects, and, therefore, the aim in the appended claims is to cover all such changes and modifications as fall Within the true spirit and scope of the invention.

I claim:

1. A cyclotron Wave-signal-energy phase shifter COIllprising:

means for projecting a stream of electrons along a predetermined axis;

means for producing a magnetic field aligned parallel to said axis;

an input coupler having signal energy input means for producing on said electron stream a cyclotron electron wave at a predetermined signal frequency;

an output coupler for deriving an output signal from said electron stream at said predetermined signal frequency;

and means adjustable during operation of the phase shifter for selectively changing the strength of said magnetic field in a region intermediate said couplers to shift the phase of said output signal with respect to that of said input signal controllably and in an amount proportional to the magnitude of strength change selected at any given time.

2. A cyclotron wave-signal-energy phase shifter comprising:

means for projecting a stream of electrons along a predetermined axis;

means for producing a magnetic field aligned parallel to said axis, said field creating for said electrons a predetermined cyclotron frequency;

an input coupler having signal energy input means for producing on said electron stream a cyclotron Wave at a predetermined signal frequency;

an output coupler for deriving an output signal from said electron stream at said predetermined signal frequency;

and means intermediate said input and output couplers and adjustable during operation of the phase shifter for selectively changing the strength of saidmagnetic field in a region intermediate said couplers to controllably alter said cyclotron frequency and shift the phase of said output signal with respect to said input signal and in an amount proportional to the magnitude of strength change selected at any given time.

3. A cyclotron wave-signaLenergy phase shifter comprising:

means for projecting a stream of electrons along a predetermined axis;

means for producing a magnetic resonance field aligned parallel to said axis;

an input coupler having signal energy input means for producing on said electron stream a cyclotron electron wave at a predetermined signal frequency;

an output coupler for deriving an output signal from said electron stream at said predetermined signal frequency;

a solenoid surrounding said axis in a region between said input and output couplers;

and means adjustable during operation of the phase shifter for passing a selectively changeable magnitude of current through said solenoid in one of the two directions through its winding for producing a secondary magnetic field of controllable intensity partially coincident with said resonance field to shift the phase of said output signal with respect to said input signal in a direction corresponding to the direction of said current and in an amount proportional to the magnitude of said current selected at any given time.

References Cited by the Examiner UNITED STATES PATENTS 9/61 Kluver 3153.6 8/62 Kompfner 315-35 X 

3. A CYCLOTRON WAVE-SIGNAL-ENERGY PHASE SHIFTER COMPRISING: MEANS FOR PROJECTING A STEAM OF ELECTRONS ALONG A PREDETERMINED AXIS; MEANS FOR PRODUCING A MAGNETIC RESONANCE FIELD ALIGNED PARALLEL TO SAID AXIS; AN INPUT COUPLER HAVING SIGNAL ENERGY INPUT MEANS FOR PRODUCING ON SAID ELECTRON STREAM A CYCLOTRON ELECTRON WAVE AT A PREDETERMINED SIGNAL FREQUENCY; AN OUTPUT COUPLER FOR DERIVING AN OUTPUT SIGNAL FROM SAID ELECTRON STREAM AT SAID PREDETERMINED SIGNAL FREQUENCY; A SOLENOID SURROUNDING SAID AXIS IN A REGION BETWEEN SAID INPUT AND OUTPUT COUPLERS; AND MEANS ADJUSTABLE DURING OPERATION OF THE PHASE SHIFTER FOR PASSING A SELECTIVELY CHANGEABLE MAGNITUDE OF CURRENT THROUGH SAID SOLENOID IN ONE OF THE TWO DIRECTIONS THROUGH ITS WINDING FOR PRODUCING A SECONDARY MAGNETIC FIELD OF CONTROLLABLE INTENSITY PARTIALLY COINCIDENT WITH SAID RESONANCE FIELD TO SHIFT THE PHASE OF SAID OUTPUT SIGNAL WITH RESPECT TO SAID INPUT SIGNAL IN A DIRECTION CORRESPONDING TO THE DIRECTION OF SAID CURRENT AND IN AN AMOUNT PROPORTIONAL TO THE MAGNITUDE OF SAID CURRENT SELECTED AT ANY GIVEN TIME. 